


Vicissitude

by knowmeknot



Category: Undertale (Video Game)
Genre: Alternate Universe - Underfell, Brotherly Love, Character Death, Contest Entry, Fellcest - Freeform, M/M, One-Sided Attraction, POV Alternating, Unrequited Love
Language: English
Status: Completed
Published: 2017-07-06
Updated: 2017-07-06
Packaged: 2018-11-28 10:03:54
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,566
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11415594
Author URL: https://archiveofourown.org/users/knowmeknot/pseuds/knowmeknot
Summary: Vicissitude (noun): a change or variation occurring in the course of something.---Feelings change and develop over time, especially love. But whether it’s familial or romantic, requited or unrequited, would you sacrifice your life for someone you love?





	Vicissitude

**Author's Note:**

> This is my submission for the fontcest contest, theme “Love”. Despite classic fontcest being an OTP of mine, I chose Fellcest since I don’t write it all that much and this concept just worked much better with it.

Papyrus secretly loved the _Fluff Bunny_ series even though he denied it all the time, calling it “MUCH TOO CHILDISH FOR THE GREAT PAPYRUS”. Though, when Sans had fought against the other Snowdin monsters to obtain the newest copy of Fluffy Bunny from the Librarby, Papyrus was unable to hide his excitement.

As part of their routine, both he and his brother snuggled into Papyrus’s four-poster bed decorated with blood-red sheets. Papyrus was small enough to fit snugly within Sans’s chin and arms. A comforting warmth flooded Papyrus’s chest whenever he and his brother did this, which wasn’t often in their hostile underground. He feared the day it would end, when he got too old for his brother’s bedtime stories.

Sans flipped opened the hand-drawn cover of a rabbit and a fox holding hands and began to read in the husky, baritone voice that always made Papyrus’s soul flutter within his chest, “fluffy bunny lived in a violent farm. the other rabbits would often fight each other.”

The page depicted a drawing of a white bunny rabbit surrounded by angry gray ones.

“fluffy bunny had a friend. his name was foxy.”

The next page had an illustration of Fluffy Bunny playing with an orangish-red fox.

“the two had known each other since childhood. they played games together, hunted together and always supported one another.”

Sans flipped the page as Papyrus snuggled closer into his brother.

“the other rabbits hate foxy and would sometimes attack him. but fluffy bunny would always be there to fight back for him.”

The page showed Foxy cowering behind Fluffy Bunny while the white rabbit bared its teeth at a larger gray rabbit.

“after spending years together, foxy fell in love with fluffy bunny. but fluffy bunny never returned foxy’s feelings.”

There was a picture of tears coming out of the fox’s eyes.

“one day, the farmer needed rabbit meat to feed his family. he decided to kill fluffy bunny—hey!”

Papyrus had flipped to the following page in anticipation. Sans barely had the chance to finish reading.

“but just as the farmer was about to cut fluffy bunny with his knife, foxy jumped in front to take the killing blow.”

The picture below the words showed Foxy lying limply on the ground surrounded by a puddle of red liquid. Fluffy Bunny stood nearby with tears in his eyes.

“the other rabbits saw what had happened, and they all attacked the farmer. they chased the farmer out. they were saved for another day. 

Sans flipped to the last page of the book.

“the rabbits had a funeral to honor foxy’s bravery. fluffy bunny was sad, but he promised to always remember his friend. the end.”

Sans closed the book, and Papyrus scoffed in disgust, clutching his small hands into fists.

“what’s up, bro? you didn’t like it?”

“NO! FOXY WAS SO DUMB! WHY WOULD HE PURPOSELY GET HIMSELF KILLED FOR FLUFFY BUNNY?!”

“think of it this way, bro, if he didn’t, then we wouldn’t be gettin’ more fluffy bunny. heh,” his brother chuckled. “pap, would you sacrifice your life for someone you love?”

Papyrus thought long and hard, and couldn’t think of any instance where he would let himself be purposely killed. In this world, giving your life in a manner other than battle was foolish and seen as weak. Papyrus was not weak!

“NO! IT’S STUPID! AND FLUFFY BUNNY DIDN’T EVEN LOVE FOXY! IT’S BASICALLY SUICIDE!”

Sans hummed in response and brought a hand to pat the top of Papyrus’s skull. Papyrus leaned into the older sibling’s touch.

“yeah, it’s pretty dumb. but y’know, for my coolest bro, i would do anything for ya.”

~*~

Papyrus didn’t know when his love for his brother morphed into something more than familial… something less brotherly and more romantic. It wasn’t like turning a light bulb, where it occurred at once. Instead, every year that went by, Papyrus’s feelings towards Sans grew. His brother was the only light in this dark underground, always supporting him and his decisions. Ever since he could remember, Sans had always taken care of him. Papyrus knew that his brother worked multiple jobs to secure the finances on their house and to provide food when other families are starving. Even when Papyrus had announced that he was going to join the Royal Guard, Sans had offered to help train him. 

His soul would pound fervently beneath his ribs every time he and Sans sparred together. The way Sans always dodged his bone attacks — the way his brother’s forehead would drip with crimson sweat and his brother’s eye lights would glitter proudly, panting heavily — sent sparks of arousal rushing to his core.

Papyrus had always thought himself as great. But in the deepest crevices of his mind, he considered his brother the greatest. 

He wanted to live the rest of his life together with his brother.

Papyrus finally admitted his feelings for his brother during one of their sparring sessions. He had been dodging Sans’s slew of bone patterns, platforms and gaster blasters. He charged towards his brother and turned Sans’s soul blue, taking him by surprise. Papyrus pinned his brother into the snow by trapping the other between his arms. He was now half a head taller than Sans.

A tinge of red dusted across Sans’s face, either by the magic exertion from their training or their position, Papyrus didn’t know. All Papyrus could think of was how amazing his brother looked beneath him. His soul pulsed with desire.

Then, barely even realizing it, Papyrus pressed his sharp teeth against his brother’s.

It was chaste, but filled with romantic intent. It felt wonderful until Sans broke the kiss and pushed him off.

“pap, wh-wha-what’re ya think yer doin’?” His brother’s breathless voice dripped with distress. “it ain’t right for us t’ be… doing _that_ kinda stuff.”

“WHY NOT? I CARE ABOUT YOU, SANS, SINCE I LOVE YOU!”

Sans bolted up and recoiled back as if struck, horror — and was that disgust? — evident on his skull. Papyrus didn’t understand why Sans reacted with such revulsion. Did Sans… not feel the same way?

“that’s wrong, pap. we’re brothers for star’s sake!” Sweat dotted Sans’s forehead, and his red eye lights were tiny pinpricks of light. He backed away from Papyrus. “i care about ya and love ya too, but only as family.” 

A sharp stab of pain rang out within Papyrus. He stood up and took a step towards his brother, who backed away with a shake of his head.

“no, pap!” Sans bowed his skull. “this was my fault. and i’m gonna fix it.”

Without another word, Sans disappeared. Papyrus stood alone in the field where they’d practiced. The rejection stung, more than anything else he’d ever felt. But he would not give up his feelings so easily.

When Papyrus got home, he found his brother staring at the TV, which was not even on! Papyrus went to sit down but froze at Sans’s raised hand.

“‘m sorry for leadin’ you to believe loving me as more than a brother is ok. it’s not,” Sans stated firmly. “to make things clear, i won’t touch ya anymore and neither should you.”

“BUT SANS—!”

“no, pap! i don’t feel the same towards ya. so please.”

Seeing the look of utter despair on his brother’s face, Papyrus reluctantly agreed.

And from then on, their training sessions ended. And Papyrus never heard another bedtime story from Sans.

~*~

Ever since Papyrus had admitted his more than platonic love for Sans, the latter maintained a fair bit of distance - both physically and mentally - between them. Sans hoped by alienating himself from his brother, Papyrus would eventually fall out of love with him. The few months following Sans’s rejection of Papyrus’s declaration were tense, and guilt gnawed at Sans’s soul every time he saw the despondent expression on his brother’s face. Despite the occasional slips, Papyrus respected Sans’s wishes and never touched him back. Instead, Papyrus threw himself into his training into becoming a Royal Guard, opting to have Undyne as his sparring partner.

Three years later, Papyrus finally became a Royal Guard. He had changed after joining the guard, becoming more distant and cold. Sans mourned over the loss of their previous warm relationship. 

Around this time was when Sans discovered alterations in the timeline - tiny blips back in time. The first occurred while Sans had been working on the machine in his secret lab. He had gone to sleep and woke up back where he’d started. Minutes became hours, and hours became days. Soon, days became months of lost time.

Sans didn’t remember all events prior to the shift back in time; only a vague sensation of deja vu and glimpses of a thorny plant ripping into monsters in his nightmares. He began to take notes, and soon realized that nothing mattered if time simply overrode everything he and his brother did. Even when the time jumps stopped, Sans never regained his motivation to do much of anything.

One day, Sans was in the middle of a dreamless nap at his sentry station when he was rudely awoken by getting thrown into the snow. He grunted in pain as his back spine hit the ground, temporarily dazed and paralyzed.

“Well, well, if it isn’t _boss’s_ brother,” Doggo’s gruff voice sneered.

Sans didn’t miss the sarcasm.

_Crack!_

A paw stomped down on Sans’s tibia and white-hot pain lanced through his right leg to the rest of his body. Sans’s vision cleared away to reveal himself surrounded by the canine unit. Doggo was the leader, with Dogamy and Dogressa flanking his side. Greater Dog towered over him while Lesser Dog stood in the rear. The pulsing agony distracted Sans from taking a shortcut out of there.

“Maybe if we hurt ya enough, your annoying brother will back down.”

Another assault almost landed, but Greater Dog’s soul turned blue, and he fell flat onto his front, pressed into the snow-covered earth. Simultaneously, jagged femurs erupted from the ground and pierced into Doggo’s hind foot.

“YOU MANGY MUTTS, GET AWAY FROM MY BROTHER AND GET BACK TO YOUR POSTS!” A sharp, furious voice ordered. 

Sans peered up and saw Papyrus standing before the canine unit, one arm outstretched with his tattered scarf billowing behind him. His black body armor, leather pants and knee-high red boots made for an imposing sight. In that moment, Sans thought his brother couldn’t look any cooler. 

“You’re wasting your time on this weakling, boss?” Dogamy asked, tone far more respectful than earlier.

“WHETHER OR NOT IT IS A WASTE OF TIME IS NOT YOURS TO DECIDE!”

Sans’s admiration for Papyrus was cut short when the latter took five paces towards where he had fallen, and glared at him with contempt. Stronger than any physical attack, Papyrus’s attitude cleaved through Sans’s soul like a knife in hot butter.

Papyrus suddenly dragged Sans up by the back of his hood and held him in the air in front of the canine unit. Sans curled inward in a futile attempt to hide his embarrassing self.

“SEE THIS? HE IS _MY PROPERTY_! YOU ARE NOT TO LAY A HAND ON HIM!”

Seeing the judging stares of the others, Sans wished he could sink into the ground.

“AND IF YOU DO, I’LL DUST YOU JUST LIKE THIS!”

Papyrus sent a barrage of five alternating length bones towards Greater Dog. As the mutt attempted to dodge away, sharp bones arose from the ground and pierced through his torso, directly into his soul. Greater Dog howled in pain and collapsed into a pile of dust. The other canine members gave various cries of distress and swiftly retreated.

Sans gaped, completely dumbstruck, at the pile of dust laying only inches away from him. Papyrus placed him back down, causing him to wince from the weight on his left leg. He looked down and saw a deep crack running diagonally along his tibia. 

“I HOPE YOU CAN WALK HOME. I AM NOT GOING TO CARRY YOU.”

Once that was said, Papyrus spun around and marched back into the direction of Snowdin. Sans was still frozen in shock by what had just happened.

His brother... Papyrus had just killed another monster without hesitation.

For him.

“ARE YOU COMING OR NOT?!” 

Sans was jolted out of his reverie, gazing at his imposing brother. Since when had Papyrus gotten so tall? A full head taller. There he stood, his entire stature tense like an overstretched rubber band. With a deep breath of unnecessary air, Sans slowly began to limp after Papyrus. His sibling didn’t take a single glance back at him, but he maintained a pace that allowed Sans to always stay several feet behind him. Sans tried to not let Papyrus’s cold shoulder get to him.

When they finally arrived at home, Papyrus stormed into the kitchen to retrieve a roll of bandages. Without turning to Sans, he flung the bandages at Sans.

“I HOPE YOU CAN FIX IT YOURSELF!” 

The taller skeleton rushed upstairs, slamming the door to his room. And in that moment, Sans realized how much of a burden he’d become to Papyrus. 

The following day, Papyrus woke Sans up early in the morning and placed a studded black collar by his bedside.

“what’s this, bro?” Sans’s soul twisted with discomfort.

“WHAT HAPPENED YESTERDAY CANNOT HAPPEN AGAIN!” Papyrus stomped his sharp boots with a click. ”AFTER MUCH THOUGHT, I’VE COME TO THE BRILLIANT CONCLUSION THAT THE BEST WAY TO KEEP YOU SAFE IS TO SHOW YOU OFF TO EVERYONE AROUND AS MY PROPERTY!”

Everything about this felt wrong, but Sans accepted it without a fuss. If this would make him less of a burden for Papyrus, this was the least he could do. 

After the collar was on, Papyrus clipped the ends of a leash to it. Sans spluttered as Papyrus pulled him out the door of his room,

“COME, LET’S BE OFF! I CANNOT DILLYDALLY TODAY! ALSO, YOU ARE TO ADDRESS ME AS ‘BOSS' FROM NOW ON. UNDERSTOOD?”

Sans nodded, wondering how everything had come to this. How their brotherly bond had deteriorated to this. 

He allowed himself to be led around the Snowdin and Waterfall area, accepting all the verbal assaults and degrading comments. Papyrus didn’t respond to them, for good or for bad, but at least no monster dared to attack him.

Sans chuckled humorlessly, and wondered if Papyrus had finally fallen out of love for him.

~*~

The human had arrived in the Underground, which wasn't a huge surprise to Sans. The time jumps restarted again, and Sans suspected it was due to the human. This time, however, they’ve been killing everyone who dared to step in their way. Sans had wondered when it would finally happen - when the kid could no longer retain their pacifist nature and become engulfed in their desire to strike back. Looks like now was the time.

The few remaining members of the canine unit have already been struck down, namely Doggo, Dogamy and Dogressa. Sans’s soul constricted painfully at the thought of Boss confronting them.

Though they’ve been in poor terms for years now, Sans still couldn't let anything happen to him. Boss was still his brother after all, no matter the harsh treatment Boss had put Sans through or how much Boss hated him now.

Before the human would get anywhere near Boss, before the human could land even a single hit on his brother, Sans planned to confront them. He would stop them. But he had to see his only family one last time.

When Sans arrived in their house, he was surprised to hear clanking of pots and pans in the kitchen. Sans peaked in and found Boss cooking.

“boss?” Sans began hesitantly. “did ya, uh, hear ‘bout the human makin’ their way to snowdin?”

“OF COURSE I DID, WHELP!” Boss snarled with a huff. 

He placed two steaming plates of spaghetti on the table. He sat down at one end and leveled Sans with an expectant glare.

“WHAT’S WITH THE DUMB LOOK? JOIN ME BEFORE YOU HEAD BACK OUT!”

Sans plopped down at the vacant seat, caught off guard by Boss’s order. It was years ago since the two of them had a meal together, Boss always busy with Royal Guard business while Sans always toiled at Grillby’s. It was actually nice that he had been given the opportunity to do this one last time. 

As Sans placed a forkful of pasta noodles and tomato sauce in his mouth, his soul gave a pang from the nostalgic taste. Around his fifth bite, drowsiness suddenly overcame him. Sans glanced up at Boss and noticed that he hadn't taken a single bite.

“wha--?”

Dark spots flickered in Sans’s vision and Boss appeared blurry. 

Did Boss put something in his food?

“Sans… I lo—”

A ringing in Sans’s ears prevented him from hearing the rest of Boss’s words, but he didn't miss the clear love in his brother’s features as darkness overtook him.

When Sans came to, he found the seat in front of him empty. Boss’s spaghetti was still untouched. A note sat on the end of the table. With panic filling his soul, Sans scrambled to pick it up. His magic ran cold at the contents of the letter.

_DEAR SANS, MY DEAREST BROTHER,_

_BY THE TIME YOU READ THIS, I'VE MOST LIKELY ALREADY CONFRONTED THE HUMAN. I DRUGGED THE FOOD, BUT I COULD NOT RISK YOU GETTING KILLED BY THE HUMAN. I’VE ALWAYS REGRET MY TREATMENT OF YOU IN THE PAST FIVE YEARS, AND I APOLOGIZE FOR IT. SINCE YOU HAD REJECTED MY AFFECTIONS, I DIDN'T KNOW HOW TO ACT AROUND YOU, AND I ONLY WANTED TO KEEP YOU SAFE, FOR US TO ALWAYS BE TOGETHER. BUT I REALIZE MY METHODS WERE WRONG. PLEASE FORGIVE ME, SANS, IF YOU CAN._

Of course, how could he not forgive him?

_BROTHER, REMEMBER WHEN YOU USED TO READ TO ME THE FLUFFY BUNNY BOOK WITH THE FOX? IT’S SO CLEAR TO ME NOW WHY FOXY GAVE UP HIS LIFE TO SAVE FLUFFY BUNNY._

Sans barely noticed the red tears that dripped onto the note. 

_I STILL LOVE YOU, SANS. EVEN AFTER ALL THESE YEARS, MY FEELINGS TOWARDS YOU REMAIN THE SAME._

_STAY SAFE, BROTHER. TO THE GREAT AND TERRIBLE PAPYRUS, YOU ARE SANSATIONAL!_

As soon as Sans finished reading, he dashed out of the house. Boss was strong; there was no way he would lose against the human. Even constant reassurance of those thoughts didn’t stop the increasing dread from filling his soul. The longer he went around Snowdin, finding no signs of his brother, the worse it got.

He came to an abrupt halt by the exit of Snowdin. His magic foze at the sight of a gray pile, easily mistaken for snow, lying in the middle of the area. The blood-red fabric of Boss’s tattered scarf gave away to whose dust that was. 

He had been wrong. Sans thought that Boss—no, Papyrus, had fallen out of love. Sans had been so afraid of returning Papyrus’s feelings, so afraid to tarnish the sibling relationship that they had together, that he had purposely closed himself off from Papyrus. And now only his dust remained.

His brother was dead. 

Overwhelming guilt and regret flooded him, and Sans collapsed limply by his brother’s dust, sobbing pitifully. Sans didn’t know how long he’d lay there, letting the coldness seep deep into his bones. Slowly, a shaky hand clutched the scarf and brought it close to his chest.

The human did this. They had killed his brother.

And for that, he was going to make them regret it. He wasn’t going to take any chances; he was going to ensure that something like this would never happen again to his beloved brother.

Sans wrapped the crimson piece of cloth around his neck and took a shortcut. He appeared in a gray room with seven containers, six of which contained a differently colored soul. Using blue magic to grab the souls in each glass canister, Sans took a shortcut into the Hall of Judgment. 

And he stood there waiting for the human. It didn’t take long, and when they finally arrived, their face, hands, and clothes were covered in dust. An ominous red knife glinted in the golden light.

Sans appeared in front of them, but kept the six souls hidden. The human’s face was completely blank, and as they sauntered towards him, their lips curled into a vicious grin.

“Are you the last line of defense before the king? How pathetic.” 

“you’ll pay for what ya did to pap, ya dirty brother killer.” Sans ran his left hand through the scarf around his neck.

“You?” they sneered. “As if you can stop me! I can just redo everything over and over until I win!”

“don’t care, ya piece of shit. i’ll do anything for pap.” 

Sans raised both arms to reveal the six souls hovering in proximity around him, and smiled at the horrified expression on the kid’s face. 

“even if i gotta fight ya for eternity. even if i gotta rewrite this whole shitty world. i’ll make sure to save my bro.”

Sans accepted the six colored souls into his own white one and attacked without holding back.

Sans didn't know the number of battles he fought against the human. Eventually, his surroundings blanketed in absolute darkness, and two words flashed before him. 

[CONTINUE] **[RESET]**


End file.
